Known covers are made of plastic material and comprise an end wall and a cylindrical sidewall for their mounting in a wheel-hub bearing, to protect from external contaminants both the bearing and a detection device of the wheel angular speed, which is coupled to the bearing.
The mounting of the cover in the bearing is realized by a press-fit operation between the sidewall and an outer ring of the bearing. Usually, the mounting sidewall is provided with a metal reinforced insert, to make stiffer the sidewall as, for example, disclosed in US 2006/159377 A1. Such a metal reinforced insert means a remarkable higher production cost of the above described covers and can also cause bi-metal problems, if in contact with the outer ring of the bearing. Therefore, recently, cheaper solutions have been realized, according to which the cover, not having anymore the known metal reinforced insert, is snap-mounted on a tubular appendage of the outer ring, thanks to snap-action locking means. Such snap-action locking means are steadily fixed to the cylindrical sidewall of the cover and are snap-engaged in a recess or in an undercut, which is formed in a cylindrical cavity of the tubular appendage.
Document EP 0 778 423 A2 discloses a cover for bearings, which is snap-mounted in a bearing case and comprises an end wall, arranged transversally with respect to the central axis of the bearing, a tapered sidewall and a seat for a seal resilient ring.
The above described covers are interposed between a detection sensor, outwardly mounted with respect to the bearing, and an encoder, inwardly mounted with respect to the bearing. Since the reading capability of the detection sensor also depends on the correct positioning of the cover, the design of both the tubular appendage of the outer ring and the snap-action locking means must be carefully realized, with very tight production tolerances, to allow a very accurate mounting of the cover.
By the way, very tight production tolerances and high accuracy of the assembling process are not suitable for current and stringent needs, requiring a reduction of both production time and costs.